ULTRASOUND TRANSDUCER MANUFACTURED BY USING MICROMACHINING PROCESS, ITS DEVICE, ENDOSCOPIC ULTRASOUND DIAGNOSIS SYSTEM THEREOF, AND METHOD FOR CONTROLLING THE SAME

• US 20090001853A1
• Filed: 09/03/2008
• Published: 01/01/2009
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: Olympus Corporation
• Original Assignee: Olympus Medical Systems Corporation (Olympus Corporation)
• Inventors: ADACHI, Hideo, FUJIMURA, Takanao, IMAHASHI, Takuya, SAWADA, Yukihiko, DOH, Ki, WAKABAYASHI, Katsuhiro, MIZUNUMA, Akiko
• Granted Patent: US 7,728,487 B2
• Time in Patent Office: Days
• US Class Current: 310/323.190
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/445 Details of catheter construction
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: B06B 1/0622 on one surface

Abstract

An ultrasound transducer manufactured by using a micromachining process comprises: a first electrode into which a control signal for transmitting ultrasound is input; a substrate on which the first electrode is formed; a second electrode that is a ground electrode facing the first electrode with a prescribed space between the first and second electrodes; a membrane on which the second electrode is formed and which vibrates and generates the ultrasound when a voltage is applied between the first and second electrodes; a piezoelectric film contacting the membrane; and a third electrode electrically continuous to the piezoelectric film.

Claims

1. An ultrasound transducer manufactured by using a micromachining process, comprising:

a first electrode into which a control signal for transmitting ultrasound is input;

a substrate on which the first electrode is formed;

a second electrode that is a ground electrode facing the first electrode with a prescribed space between the first and second electrodes;

a membrane on which the second electrode is formed and which vibrates and generates the ultrasound when voltage is applied between the first and second electrodes;

a piezoelectric film contacting the membrane; and

a third electrode jointed to the piezoelectric film.

2. The ultrasound transducer according to claim 1, wherein:

the piezoelectric film is stacked and arranged on a surface of the membrane.

3. The ultrasound transducer according to claim 1, wherein:

the piezoelectric film is a supporting member for supporting the membrane.

4. The ultrasound transducer according to claim 2, wherein:

the third electrode is formed on one surface of the piezoelectric film, and the second electrode is formed on the other surface of the piezoelectric film.

5. The ultrasound transducer according to claim 1, wherein:

the piezoelectric film is a piezoelectric material that does not contain lead.

6. The ultrasound transducer according to claim 5, wherein:

the piezoelectric material is one of aluminum nitride, zinc oxide, barium titanate, and barium strontium titanate.

7. The ultrasound transducer according to claim 3, further comprises:

a supporting member for supporting the membrane, said supporting member being arranged along a node of fundamental vibration obtained when the membrane vibrates freely.

8. The ultrasound transducer according to claim 2, wherein:

one end of the third electrode is provided so that said one end reaches a periphery of the membrane, and the other end of the third electrode extends at least to a center of the membrane.

9. The ultrasound transducer according to claim 1, wherein:

the piezoelectric film is a first piezoelectric film stacked and arranged on a surface of the membrane and a second piezoelectric film formed as a supporting member for supporting the membrane;

the third electrode is formed on one surface of the first piezoelectric film, and the second electrode is formed on the other surface of the first piezoelectric film; and

the ultrasound transducer further comprises;

a fourth electrode which is connected to the second piezoelectric film and into which the control signal is input.

10. The ultrasound transducer according to claim 9, wherein:

the second piezoelectric film as the supporting member supports an end of the membrane; and

when ultrasound that has been received by the membrane is converted into a pulse signal by the first piezoelectric film, damping is performed on a tailing portion of the pulse signal by applying to the fourth electrode the control signal for cancelling the tailing portion of the pulse signal.

21. An Endoscopic ultrasound diagnosis system comprising the ultrasound transducer according to claim 1.

22. The Endoscopic ultrasound diagnosis system according to claim 21, wherein:

the Endoscopic ultrasound diagnosis system is an ultrasound endoscope.

23. The Endoscopic ultrasound diagnosis system according to claim 21, wherein:

the ultrasound transducer is used as a miniature ultrasound probe inserted into a forceps opening of an endoscope.

24. The Endoscopic ultrasound diagnosis system according to claim 21, wherein:

the ultrasound transducer is used as an intravascular ultrasound probe.

25. The Endoscopic ultrasound diagnosis system according to claim 21, wherein:

the ultrasound transducer is used as an ultrasound capsule endoscope.

11. An ultrasound transducer device manufactured by using a micromachining process having an ultrasound transducer comprising:

a first electrode into which a control signal for transmitting ultrasound is input;

a substrate on which the first electrode is formed;

a second electrode that is a ground electrode facing the first electrode with a prescribed space between the first and second electrodes;

a membrane on which the second electrode is formed and which vibrates and generates the ultrasound when voltage is applied between the first and second electrodes;

a first piezoelectric film formed on the second electrode formed on a surface of the membrane; and

a third electrode that is connected to the first piezoelectric film and faces the second electrode via the piezoelectric film, said ultrasound transducer device comprising;

a conversion unit boosting an alternating current low voltage signal conveyed from a conveying cable, and converting it into a direct current voltage signal;

a first switching unit switching an electrical connection between the conversion unit and the first electrode;

a self oscillating unit performing self-oscillation on the basis of the direct current voltage signal input into the first electrode in order to drive the ultrasound transducer to transmit ultrasound;

a reception signal processing unit performing a prescribed signal process on a reception signal created on the basis of the ultrasound received by the ultrasound transducer; and

a second switching unit switching an electrical connection between the conversion unit and the reception signal processing unit.

12. The ultrasound transducer device according to claim 11, wherein:

the first switching unit and the second switching unit are respectively turned on and turned off when transmitting ultrasound, and are respectively turned off and turned on when receiving ultrasound.

13. The ultrasound transducer device according to claim 12, wherein:

the first switching unit and the second switching unit are a pair of electronic switches.

14. The ultrasound transducer device according to claim 13, wherein:

the first switching unit and the second switching unit are integrated on a surface of the substrate or in the substrate.

15. The ultrasound transducer device according to claim 11, wherein:

the ultrasound transducer further comprises;

a piezoelectric supporting member for supporting the membrane formed of a second piezoelectric film; and

a fourth electrode into which the direct current voltage signal for driving the piezoelectric supporting member is input.

16. The ultrasound transducer device according to claim 11, wherein:

the self oscillating unit;

is a positive feedback circuit including at least an amplification element for amplifying the feedback signal and the ultrasound transducer; and

inputs, into the amplification element as a feedback signal, a voltage signal generated from the first piezoelectric film corresponding to deformation of the membrane activated by applying the direct current voltage signal between the first electrode and the second electrode.

17. The ultrasound transducer device according to claim 16, wherein:

the self oscillating unit further comprises;

a phase adjustment element for adjusting phases of the feedback signal in a stage earlier than the amplification element.

18. The ultrasound transducer device according to claim 16, wherein:

the self oscillating unit further comprises;

a high-frequency wave removal unit removing a high-frequency wave corresponding to a high-order vibration mode.

19. The ultrasound transducer device according to claim 11, wherein:

the reception signal processing unit includes;

a charge amplification unit detecting the reception signal that is a charge signal;

an impedance conversion unit converting the reception signal having a high impedance into a reception signal having a low impedance; and

a voltage amplification unit amplifying the voltage of the reception signal.

20. The ultrasound transducer device according to claim 11, wherein:

the ultrasound transducer, the self oscillating unit, the reception signal processing unit, the first switching unit, and the second switching unit are integrated on the substrate.

26. An Endoscopic ultrasound diagnosis system including the ultrasound transducer device according to claim 11.

27. The Endoscopic ultrasound diagnosis system according to claim 26, wherein:

the Endoscopic ultrasound diagnosis system is an ultrasound endoscope.

28. The Endoscopic ultrasound diagnosis system according to claim 26, wherein:

the ultrasound transducer device is used as a miniature ultrasound probe inserted into a forceps opening of an endoscope.

29. The Endoscopic ultrasound diagnosis system according to claim 26, wherein:

the ultrasound transducer device is used as an intravascular ultrasound probe.

30. The Endoscopic ultrasound diagnosis system according to claim 26, wherein:

the ultrasound transducer device is used as an ultrasound capsule endoscope.

31. A method of controlling an ultrasound transducer manufactured by using a micromachining process, comprising:

a first electrode into which a control signal for transmitting ultrasound is input;

a substrate on which the first electrode is formed;

a second electrode that is a ground electrode facing the first electrode with a prescribed space between the first and second electrodes;

a membrane on which the second electrode is formed and which vibrates and generates the ultrasound when voltage is applied between the first and second electrodes;

a first piezoelectric film formed on the second electrode formed on a surface of the membrane; and

a third electrode contacting the first piezoelectric film and facing the second electrode via the piezoelectric film, wherein;

the piezoelectric film stacked and arranged on a surface of the membrane detects deformation of the membrane that deforms corresponding to the control signal input into the first electrode.

32. The method of controlling an ultrasound transducer according to claim 31, wherein:

the ultrasound transducer further comprises;

a piezoelectric supporting member for supporting the membrane formed of a second piezoelectric film; and

a fourth electrode into which the control signal for driving the piezoelectric supporting member is input, wherein;

ultrasound is transmitted by deformation of the membrane vibrating on the basis of voltage applied between the first and second electrodes and by deformation of the piezoelectric supporting member by voltage applied to the fourth electrode.

33. A method of controlling an ultrasound transducer device manufactured by using a micromachining process, comprising:

an ultrasound transducer including;

a first electrode into which a control signal for transmitting ultrasound is input;

a substrate on which the first electrode is formed;

a second electrode that is a ground electrode facing the first electrode with a prescribed space between the first and second electrodes;

a membrane on which the second electrode is formed and which vibrates and generates ultrasound when voltage is applied between the first and second electrodes;

a first piezoelectric film formed on the second electrode formed on a surface of the membrane; and

a third electrode connected to the first piezoelectric film and facing the second electrode via the piezoelectric film; and

a conversion unit boosting an alternating current low-voltage signal conveyed from a conveying cable, and converting it into a direct current voltage signal;

a first switching unit switching an electrical connection between the conversion unit and the first electrode;

a self oscillating unit performing self-oscillation on the basis of the direct current voltage signal input into the first electrode in order to drive the ultrasound transducer to transmit ultrasound;

a reception signal processing unit performing a prescribed signal process on a reception signal created on the basis of the ultrasound received by the ultrasound transducer; and

a second switching unit switching an electrical connection between the conversion unit and the reception signal processing unit, wherein;

when transmitting ultrasound, the first switching unit is turned on and the second switching unit is turned off;

an alternating current voltage signal for controlling vibration of the membrane is boosted by the conversion unit in order to convert it into a direct current voltage signal;

the direct current voltage signal is supplied to the self oscillating unit via the first switching unit; and

ultrasound is transmitted from the ultrasound vibration on the basis of the self oscillating unit.

34. The method of controlling an ultrasound transducer device according to claim 33, further comprising:

turning off the first switching unit and turning on the second switching unit when receiving ultrasound;

receiving ultrasound by the ultrasound transducer and converting the received ultrasound into an electric signal;

conveying the reception signal converted into the electric signal to the reception signal processing unit; and

amplifying the voltage of the reception signal by the reception signal processing unit, and performing impedance conversion.

35. The method of controlling an ultrasound transducer device according to claim 33, wherein:

the ultrasound transducer further comprises;

a piezoelectric supporting member for supporting the membrane formed of a second piezoelectric film; and

a fourth electrode into which the control signal for driving the piezoelectric supporting member is input; and

deformation of the membrane vibrating on the basis of voltage applied between the first and second electrodes and deformation of the piezoelectric supporting member by voltage applied to the fourth electrode are superposed so that the deformations are in phase so that ultrasound is transmitted.